Comcast Cisco RNG200n external HD suggestion Please

You need to call Comcast and ask them. They only very recently announced that they would begin supporting external drives and it's unlikely that it's been implemented in your area yet.

Until that very recent announcement, It has been very unusual for cable companies in the US to support external drives.

The thought people had already been adding the 1TB (maximum) esata drives to the RNG200? I read a couple of messages here, but I haven't bothered to implement it yet.

Maybe. I'm not sure. But in the recent past there were very few customers in the US able to use external storage with their DVR's. The cable company must enable the feature, which requires them to push out a new firmware/software version. It would be a good idea to contact your cable company and ask if that has happened (though you may have to fight through first-level support to get someone who knows what they're talking about.)

Well I can now confirm the WD MY Book AV DVR expander works with Comcast's RNG200. No contact with the cable company was required. Unplugged my RNG200, attached the esata cable of the WD to the RNG, plugged in the power adapter of the WD and then plugged the RNG200 back on. After a few minutes, a screen comes up asking if you want to format the drive. (Yes or Cancel). The only problem is that which option is actually highlighted is not clear. I hit ok the first time, but my DVR was still 81% full, so I knew something was wrong although going through a list of my recordings was MUCH faster. Anyway I just unplugged my RNG200 again and waited for the format screen. Moved between both options to confirm that it's nearly impossible to tell which option you have actually selected, then did the opposite of last time. Voila, I'm now at 0% full and the RNG confirms it's using external storage.